The purpose of this study is to investigate the interrelationship between headache symptoms and features and their association with the four major types of headache, and to explore the development of a new classification system of headache based on objective criteria. The data for these analyses were collected in a feasibility study. In the feasibility study a detailed survey questionnaire was developed which included sections on demography, descriptive headache features, medical information, and history. Lengthy telephone interviews were conducted with patients from four headache clinics. Preliminary results show that the statistical technique of discriminant analysis can correctly classify most cases of headache into four major types. Factor and cluster analyses will be used to determine objectively, syndromes corresponding to the different headache types and to determine groups of related headache symptoms and features which can be used in an operational classification of headache types.